Well, I know I have visited many National Park Service locations, but never made a list. I used the
"Find a Park" section of the National Park Service page to put together this list.
National Parks:
Acadia, ME
Arches, UT
Badlands, SD
Bryce Canyon, UT
Canyonlands, UT
Capitol Reef, UT
Carlsbad Caverns, NM
Crater Lake, OR
Death Valley, CA
Everglades, FL
Glacier, MT
Grand Canyon, AZ
Grand Teton, WY
Great Basin, NV
Great Falls, VI
Great Sand Dunes, CO
Great Smoky Mountains, NC
Joshua Tree, CA
Kings Canyon, CA
Lassen Volcanic, CA
Mammoth Cave, KY
Mesa Verde, CO
Mount Rainier, WA
North Cascades, WA
Olympic, WA
Petrified Forest, AZ
Redwood, CA
Rocky Mountain, CO
Sequoia, CA
Shenandoah, VA
Wind Cave, SD
Yellowstone, WY
Yosemite, CA
Zion, UT
National Monuments unless noted:
Agate Fossil Beds, NE
Canyon de Chelly, AZ
Cape Cod, MA (National Seashore)
Cape Hatteras (National Seashore)
Cape Lookout, NC (National Seashore)
Cedar Breaks, UT
Chiricahua, AZ
Craters of the Moon, ID
Deleware Water Gap, NJ, PA (National Recreation Area)
Devils Tower, WY
Dinosaur, CO
Effigy Mounds, lA
Erie Canalway, NY (National Heritage Corridor)
Franklin Delano Roosevelt, DC (Memorial)
Fire Island, NY (National Seashore)
Fort Pulaski, GA
Fort Stanwix, NY
Gauley River, WV (National Recreation Area)
Glen Canyon, AZ, UT (National Recreation Area)
Jewel Cave, SD
John Day Fossil Beds, OR
Korean War Veterans, DC (Memorial)
Lava Beds, CA
Lincoln Boyhood, IN
Little Bighorn Battlefield, MT
Mount St. Helens, WA
Natchez Trace, AL, MS, TN
National Mall, DC
Natural Bridges, UT
Niagara Falls, NY (National Heritage Area)
Pipe Spring, AZ
Pony Express, NE (National Historic Trail)
Potomac Heritage, DC (National Scenic Trail)
San Juan Island, WA (National Historic Park)
Statue of Liberty, NY
Vietnam Veterans, DC (Memorial)
Washington Monument, DC
White Sands, NM
Wright Brothers, NC (National Memorial)
It is difficult to leave out the wonderful state parks around the US - many are as breath taking as the National Parks & Monuments. I've visited many; some worth pointing out:
Antelope Canyon (Navajo Reservation, AZ)
Babcock State Park, WV
Burney Falls State Park, CA
Caverns of Sonora, TX (Not a park, but one of the prettiest caves I've been to)
City of Rocks State Park, NM
Dead Horse Point State Park, UT
Goblin Valley State Park, UT
Hanging Lake, CO
Kodachrome Basin State Park, UT
Letchworth State Park, NY
Lost Dutchman State Park, AZ
Mono Lake, CA
Palouse Falls, WA
Red Rock Canyon, CA
Ricketts Glen State Park, PA (My Favorite)
Silver Falls, OR
Valley of Fire State Park, NV
I have links to photos of some of the National & State parks
here.